Police informed Townshend at noon, and as a routine part of the cautioning process, took fingerprints, a photograph and a DNA sample.

Standard procedure in these cases provides that Townshend will be entered on the Sex Offenders Register for a period of five years.

The formal cautioning -- short of a criminal charge but an official warning that next time charges would almost certainly follow -- came after four months of investigation by officers from Scotland Yard's Child Protection Group.

Townshend, guitarist and songwriter for the rock group, The Who, said he had looked at the front pages and previews of child pornography sites perhaps three or four times in 1999 after accidentally stumbling across one. He was later arrested.

It is illegal to look at such sites in Britain. Prosecution can result in a prison term of up to five years. (The law)

Police established that Townshend was not in possession of any downloaded child abuse images and said "he fully co-operated with the investigation." (Profile)

They added the decision to "caution" was made in accordance with police case disposal methods, and with all available evidence and the Home Office Sentencing Advisory Panel guidelines.

Townshend had previously admitted viewing child pornography but said it was only for research purposes because he was writing a book.

He was taken into police custody January 14, but was released on bail.

"I am not a pedophile," he has repeatedly insisted.

In a statement Wednesday, he said: "From the very beginning, I acknowledged that I did access this site and that I had given the police full access to all of my computers."

He added "As I made clear at the outset, I accessed the site because of my concerns at the shocking material readily available on the Internet to children as well as adults, and as part of my research toward the campaign I had been putting together since 1995 to counter damage done by all kinds of pornography on the Internet, but especially any involving child abuse."

He said: "The police have unconditionally accepted that these were my motives in looking at this site and that there was no other nefarious purpose, and as a result they have decided not to charge me.

"I accept that I was wrong to access this site, and that by doing so, I broke the law, and I have accepted the caution that the police have given me."

Townshend's is the highest-profile case to be made public yet of the 1,300 arrests British police have made since last summer as they trawl through a list of some 6,500 Britons suspected of illegally accessing Internet sites.

Townshend helped found The Who in the 1960s, and wrote most of the band's hits, including "My Generation," "Pinball Wizard" and "Won't Get Fooled Again."

Townshend became legendary for his whirlwind moves and guitar-smashing rampages on stage. The band was inducted into the Rock 'n' Roll Hall of Fame in 1990.

The last year has been filled with sadness for the band. Bassist John Entwistle died of an apparent heart attack related to cocaine use in June in Las Vegas, Nevada.